Smoking is the leading cause of preventable morbidity and mortality in the United States. Moreover, smoking is a critically significant behavioral risk factor that contributes to social disparities in the incidence and mortality of disease. That is, because the prevalence of smoking is higher among individuals with lower socioeconomic status, smoking has a substantial influence on socioeconomic disparities in health- related morbidity and mortality. Therefore, connecting underserved smokers with evidence-based tobacco cessation programs is crucial for disease prevention and the elimination of health disparities. Telephone- based counseling for smoking cessation delivered via quitlines has demonstrated considerable efficacy. However, quitlines are grossly underutilized. Referrals to quitlines generated in primary care settings are low, and a large majority of smokers referred to quitlines fail to contact the quitlines on their own for cessation assistance. Thus, the focus of this study is on increasing dissemination of an existing evidence- based smoking cessation program, the State of Texas Quitline (i.e., Quitline), which is provided by the American Cancer Society. The design of the study is a group-randomized trial that will be conducted in 10 community health clinics. Clinics are part of the Harris County Hospital District (HCHD) and provide care to a very large, racially/ethnically diverse, low socioeconomic status, underserved population of patients residing in the Houston metropolitan area. Clinics will be randomized to either an "Ask-Advise-Connect" or an "Ask-Advise-Refer" dissemination approach. Smoking status will be assessed and recorded in the electronic medical record (EMR) at every patient visit, and smokers will be connected (in the Ask-Advise- Connect condition) or referred (in the Ask-Advise-Refer control condition) to the Quitline through an automated link contained in the EMR. Smokers in the Ask-Advise-Connect condition will be called proactively by the Quitline, and smokers in the Ask-Advise-Refer condition will be encouraged to call the Quitline on their own. All smokers will be offered a series of proactive counseling calls during their initial call with the Quitline. The project will involve a close partnership and collaboration with the HCHD community health clinics. Outcome measures are based on the RE-AIM conceptual framework and are consistent with current dissemination research models. Primary outcomes include reach, efficacy, and impact of the dissemination approaches. Secondary outcomes include patient-reported fidelity as well as acceptance of and barriers to dissemination of the Quitline among clinic staff. The Ask-Advise-Connect approach to dissemination of an evidence-based tobacco cessation program could be easily maintained by the HCHD clinics and adopted by other health care settings. Thus, findings are likely to have a significant public health impact.